/*
 * Copyright 2013 The Netty Project
 *
 * The Netty Project licenses this file to you under the Apache License,
 * version 2.0 (the "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at:
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 */
package io.netty.buffer;

import java.nio.ByteOrder;

/**
 * A {@link ByteBuf} implementation that wraps another buffer to prevent a user from increasing or
 * decreasing the wrapped buffer's reference count.
 */
final class UnreleasableByteBuf extends WrappedByteBuf {

  private SwappedByteBuf swappedBuf;

  UnreleasableByteBuf(ByteBuf buf) {
    super(buf instanceof UnreleasableByteBuf ? buf.unwrap() : buf);
  }

  @Override
  public ByteBuf order(ByteOrder endianness) {
    if (endianness == null) {
      throw new NullPointerException("endianness");
    }
    if (endianness == order()) {
      return this;
    }

    SwappedByteBuf swappedBuf = this.swappedBuf;
    if (swappedBuf == null) {
      this.swappedBuf = swappedBuf = new SwappedByteBuf(this);
    }
    return swappedBuf;
  }

  @Override
  public ByteBuf asReadOnly() {
    return buf.isReadOnly() ? this : new UnreleasableByteBuf(buf.asReadOnly());
  }

  @Override
  public ByteBuf readSlice(int length) {
    return new UnreleasableByteBuf(buf.readSlice(length));
  }

  @Override
  public ByteBuf readRetainedSlice(int length) {
    // We could call buf.readSlice(..), and then call buf.release(). However this creates a leak in unit tests
    // because the release method on UnreleasableByteBuf will never allow the leak record to be cleaned up.
    // So we just use readSlice(..) because the end result should be logically equivalent.
    return readSlice(length);
  }

  @Override
  public ByteBuf slice() {
    return new UnreleasableByteBuf(buf.slice());
  }

  @Override
  public ByteBuf retainedSlice() {
    // We could call buf.retainedSlice(), and then call buf.release(). However this creates a leak in unit tests
    // because the release method on UnreleasableByteBuf will never allow the leak record to be cleaned up.
    // So we just use slice() because the end result should be logically equivalent.
    return slice();
  }

  @Override
  public ByteBuf slice(int index, int length) {
    return new UnreleasableByteBuf(buf.slice(index, length));
  }

  @Override
  public ByteBuf retainedSlice(int index, int length) {
    // We could call buf.retainedSlice(..), and then call buf.release(). However this creates a leak in unit tests
    // because the release method on UnreleasableByteBuf will never allow the leak record to be cleaned up.
    // So we just use slice(..) because the end result should be logically equivalent.
    return slice(index, length);
  }

  @Override
  public ByteBuf duplicate() {
    return new UnreleasableByteBuf(buf.duplicate());
  }

  @Override
  public ByteBuf retainedDuplicate() {
    // We could call buf.retainedDuplicate(), and then call buf.release(). However this creates a leak in unit tests
    // because the release method on UnreleasableByteBuf will never allow the leak record to be cleaned up.
    // So we just use duplicate() because the end result should be logically equivalent.
    return duplicate();
  }

  @Override
  public ByteBuf retain(int increment) {
    return this;
  }

  @Override
  public ByteBuf retain() {
    return this;
  }

  @Override
  public ByteBuf touch() {
    return this;
  }

  @Override
  public ByteBuf touch(Object hint) {
    return this;
  }

  @Override
  public boolean release() {
    return false;
  }

  @Override
  public boolean release(int decrement) {
    return false;
  }
}
